When a contract is made by email the usual rules of offer, revoking (an offer), acceptance, refusal, counter offer, conditional offer ect is that usually any one of these is complete when it is received by the recipient.

what happens when email is used?does it have to be proved that it arrived in a persons inbox?does it have to be proved that they opened it?does it have to be proved that the read it?

What happens if one party can prove an email was sent but the other simply denies receiving it?

what about in the case of a unilateral offer where the condition to be met is to send some information (say proof of owenership)if such proof was sent by email at what point would this condition be "proved".

The postal rule is an exception. it only applies to acceptance (not offer or rejection/revocation) and states that a letter is considered to have arrived as soon as it is sent.it also, as the name suggests, only applies to postal communication - so has no relevance to email

There may very well be a difference between sending an email and posting a letter which is recognised in law. A letter is committed to the Royal Mail who have a statutory duty in its delivery. An email may be split into many parts and sent via a dozen intermediaries before being received.